In recent telecommunication networks, communication of very different character takes place simultaneously. Small packet flows, such as e.g. Voice over Internet Protocol (VoIP) or small objects transferred over the Transmission Control Protocol (TCP), such as chat or gaming, are mixed with larger data quantities e.g. large File Transfer Protocol (FTP) downloads. Such an inhomogeneous mix of traffic occurs in particular in the downlink (DL) signaling, i.e. from an eNodeB to a User Equipment (UE). Typically, an eNode B has access to different bearers and the traffic is divided between these bearers.
The current state of the art algorithms in Long-Term Evolution (LTE) systems put the flows belonging to a specific radio bearer into a queue. The queue is controlled by different kinds of Active Queue Management (AQM) algorithms. This approach operates well if the flows have roughly the same properties, for instance, two large file downloads can cooperate well. However, at occasions where small and fast flows compete with large file downloads and possibly also downloads of larger domain sharded websites, the effect will often be that the small and fast flows suffer from high latency and or packet loss. The small and fast flows, which often are delay sensitive, will then suffer from poor Quality-of-Experience (QoE).
This problem can be mitigated somewhat by making the queue short, which translates to e.g. low delay thresholds in the AQMs. The drawback of this approach is, however, that it can degrade throughput and it typically also increases the packet loss rates, which can be detrimental for small TCP transfers as it takes a round trip to retransmit the missing TCP segments.
Another way of mitigating this problem would be to put the delay sensitive short and fast flows in separate bearers, and possibly let them have a higher scheduling priority. Ideas like this, however, seem to have difficulties in their realization. Possible reasons are that they require a classification engine and also additional signaling to set up bearers for these short and fast flows, which often may have a very short lifetime. The overall management processing thereby may be extremely high.